CN1206521A - Method, transmitter and receiver for transmitting training signals in TDMA transmission system - Google Patents
Method, transmitter and receiver for transmitting training signals in TDMA transmission system Download PDFInfo
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- CN1206521A CN1206521A CN 96199426 CN96199426A CN1206521A CN 1206521 A CN1206521 A CN 1206521A CN 96199426 CN96199426 CN 96199426 CN 96199426 A CN96199426 A CN 96199426A CN 1206521 A CN1206521 A CN 1206521A
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Abstract
The invention relates to a TDMA method, transmitter and receiver, wherein a training sequence is modulated and superposed on a data signal to thereby generate a TDMA burst. Thereby, the training sequence can be made longer and is always available during data reception, such that longer channel impulse responses can be measured. In the transmitter, the training sequence is separately modulated in a modulating means before being superposed on the data signal. The receiver comprises an extracting means for extracting the superposed training sequence and a cancelling means for cancelling the training sequence from the data signal to be detected.
Description
Invention field
The present invention relates to a kind of TDMA (time division multiple access) method, transmitter and receiver.Particularly, the present invention relates to a kind of digital mobile communication system, as gsm system (mobile communication special group) or DCS (Digital Cellular System).
Background of invention
In the TDMA of digital mobile communication system class, the shared carrier wave of several users.On this carrier wave, each user is assigned with one section time slot separated from one another, is used for transmitting and receiving the short burst sequence of packet that protected time-division is opened.Number of users on carrier wave is limited to the number of timeslots of distributing to that specific carriers.
Gsm system was described, for example at " gsm system that is used for mobile communication ", and M.Moyly and M.-B.Pautet, Palaiseau, France, 1992, ISBN:2-9507190-0-7, thereby not for a more detailed description at this.
In the current GSM system, for example described in document WO-A-95/28771, a predetermined bit sequence is used as training sequence in the middle of the data in TDMA burst sequence, with it is in order to calculate the impulse response parameter of each channel, promptly to estimate channel impulse response tap gain coefficient.These parameters are used to remove the interaction that is caused by the multipath transmission.
At present, by available training sequence, about 5 tap gain coefficients of channel impulse response can be measured.If longer impulse response is measured, then will need a kind of longer training sequence, this will reduce the data in the TDMA burst sequence.
Consider the problem of the efficiency of transmission minimizing relevant with using long training sequence more, the preposition word of training in document EP-A-0355587 suggestion cancellation TDMA burst sequence, and in estimating clock and carrier phase, the sampled data of base band quadrature signal component as whole time slot is stored in the time-delay buffer.Yet in this case, need complicated signal processing circuit to be used for obtaining desired estimation.
Summary of the invention
The purpose of this invention is to provide a kind of improved TDMA method, transmitter and receiver can be measured longer impulse response by them.
This purpose realizes that by a kind of TDMA method this method may further comprise the steps: a modulation training sequence and a training sequence of modulation are superimposed upon and produce TDMA burst sequence on the data-signal.
Further, this purpose is to realize by a kind of transmitter that is used for tdma system, this transmitter comprises the modulating device that is used to modulate training sequence, be used for by the training sequence of modulation being added in the stacking apparatus that produces TDMA burst sequence on the data-signal and being used to launch the emitter of said TDMA burst sequence.
This purpose is to realize by a kind of receiver that is used for tdma system in addition, this receiver comprises the receiving system that is used to receive TDMA burst sequence, be used for extracting the extraction element of the training sequence that is applied and being used for before Data Detection, removing the removal device of the training sequence that is applied from the TDMA burst sequence that receives.
Since training sequence is to be superimposed on the TDMA burst sequence, one may also can be used by the same long long training sequence with whole burst sequence.Therefore, training sequence is always available, is used for measuring longer or shorter channel impulse response.
Another advantage is any variation that such training sequence can be used to the channel impulse response on estimated frequency error and the burst sequence,
Method of the present invention, the preferred embodiment of transmitter and receiver can obviously be seen from the dependent claim that is attached to the back.
The accompanying drawing summary
Below, with reference to accompanying drawing, the present invention and a kind of embodiment preferred will be described in more detail, and accompanying drawing has:
Fig. 1 represents a kind of TDMA burst sequence according to prior art,
Fig. 2 represents a kind of according to TDMA burst sequence of the present invention, and
Fig. 3 is the block diagram according to the tdma system transmitter and receiver of one embodiment of this invention.
As shown in Figure 1, according to the GSM technical specification, a kind of known TDMA burst sequence comprises by separated two message segments of training sequence (26 bit) (58 bit) in the middle of the burst sequence.In addition, the burst sequence comprises short (3 bit) beginning sequence and in the ending sequence of ending place of burst sequence.
Fig. 2 represents according to TDMA burst sequence of the present invention, and wherein, long training sequence is provided, and it is in the centre of data, and on data (or better below), and it has less power.It is specially adapted to have the system of long burst sequence, because in this case, training sequence can long enough thereby can be launched with less power.Beginning and ending sequence can still be retained in this new structure.
As training sequence, those are used for the sequence of gsm system or longer CAZAC sequence, as (being published in IEEETransactions on Information Theory at " almost ideal autocorrelation sequence " by Jacques Wolfmann, Vol.38, No.4, those sequences or the M sequence that are suggested in July) can be used.Modulated and the stack of this sequence for example is added on the data-signal.If these sequences fall short of, then it can be repeated periodically.In this case, need good cycle autocorrelation performance.This cycle should long enough to guarantee to measure the quantity of the channel impulse response tap gain coefficient that is required.If the cycle of training sequence is 32 bits, so maximum 15 tap gain coefficients can be measured.This uses great majority is enough.
According to the present invention, since all training sequence can be longer, whole sequence can repeatedly be repeated, therefore, and whole training sequence or have only its part can be used to channel estimating.
On the other hand, the cycle should be not oversize, so that training sequence can be used to the estimated frequency error, and promptly can be measured to derive phase change and other variation at several somes upper signal channel impulse responses along the burst sequence.
The power of the training sequence that is applied should be enough little of to stop the excessive interference to the TDMA data-signal of modulation.Yet power should arrive greatly realizes reliable channel estimating.Power also depends on the length of burst sequence.In fact, the power of training sequence should be below signal power 0 to 10dB.
The block diagram that Fig. 3 represents comprises transmitter unit in one embodiment of this invention and those parts of receiver unit, is important for understanding the present invention.
According to the top of Fig. 3, transmitter unit comprises the burst sequence generating device 1 that is used for according to being provided to the input data generation burst sequence here.The burst sequence that produces is modulated in first modulating device.In addition, second modulating device 3 is provided and is used for modulating respectively the training sequence that is provided.The training sequence of being modulated is attenuated in for example adjustable attenuator 4, selects the decay factor of attenuator 4 so that the interference of data burst sequence is reduced to minimum and guaranteed that authentic data detects.Modulation training sequence through decay is added on the data burst sequence of modulation.This can be by for example realizing two modulation signal phase Calais.
If Gaussian-filtered minimum shift keying (GMSK) is used as the modulator approach of transmission, the stack of data burst sequence and training sequence preferably is performed on the intermediate frequency rank.
If linear modulation is used in the tdma system, the stack of data burst sequence and training sequence also can be performed on baseband level.
The modulator approach of training sequence and data burst sequence also can differ from one another, as long as ensuing separation is feasible and does not have too much deterioration.For the whole channel of energy measurement, same modulating frequency is preferably used in the modulation of above-mentioned data burst sequence and training sequence.
Filtered device 5 filtering of result's composite signal are so that limit transmission bandwidth according to the requirement of corresponding system.The combination that obtains from filter 5 and the tdma signal of filtering are provided for radio frequency (RF) emitter 6 then, and it is by using the transmission antennas transmit composite signal as RF burst sequence.
Receiver unit in the bottom of Fig. 3 comprises RF receiving system 7, and it receives RF burst sequence with reception antenna.The RF burst sequence of RF receiving system 7 by using local oscillator (not shown) demodulate reception to arrive.The tdma signal of demodulation is with filter 8 filtering, to remove undesired frequency component.The TDMA composite signal that receives is branched, and by using a kind of filter (not shown) as sef-adapting filter, the training sequence of stack is extracted and detects by channel estimating apparatus 11.
The kind of extracting depends on the autocorrelation performance of training sequence.If training sequence has good autocorrelation performance, so simple matched filter/correlation technique just can be used, and promptly signal training sequence with known in receiver is relevant.Because good autocorrelation performance, this relevant output are that channel estimating adds the noise that is produced by random data signals, from other user's interference and Gaussian noise.Training sequence can be any random sequence, but will need more complicated method of estimation like that.Therefore, good sequence is preferred.
The training sequence that detects is made by said channel estimating apparatus 11 and is used for measuring desired channel impulse response parameter.
In another branch, by removal device 11, training sequence is removed from the data burst sequence that receives.According to the tested channel impulse response parameter that is offered training sequence removal device 9 by above-mentioned channel estimating apparatus 11, removal can realize by disturbing the removal technology.In training sequence removal device 11, training sequence can be reproduced from received signal before Data Detection and be deducted.
As an alternative, under the situation of permanent envelope data modulation, the removal of training sequence can be by simply blocking or the restriction technologies realization.Therefore, any interference in the ensuing Data Detection can be prevented from.
After the training sequence of stack is removed from the burst sequence that is received, offer the channel impulse response parameter of detector 10 according to channel estimating apparatus 11, Data Detection is performed at detector 10.At last, detector 10 is exported the data that received.Conventional sense device such as MLSE detector (Viterbi), DFE detector etc. all can be used as detector 10.
By a kind of receiver that utilizes iteration is provided, the present invention can further be modified.Wherein, channel estimating and Data Detection are performed earlier, next are to receiving the estimation of data, and it can be used to the data-signal of regenerating and being received, and promptly along with channel estimating, the bit of detection is separated mediation filtering.The data-signal of being regenerated can deduct from the signal that is received, and a kind of new channel estimating can be performed.Under the correct situation of most of data bits, this processing can improve channel estimating.This causes improved training sequence to be removed and Data Detection.Above-mentioned iterative process can repeatedly be repeated, till reaching the improvement of wanting.
Be the measuring frequency error, in the different piece of data burst sequence, by only using the part of training sequence, the channel estimating of separation is performed.Next, the phase error between channel estimating can be measured and be used as the indication of frequency error.
Description and accompanying drawing are just hoped the present invention that explains through diagrams above should be appreciated that.Therefore, the method according to this invention also can be used to the system outside the described gsm system.Therefore, method of the present invention, the preferred embodiment of Receiver And Transmitter can change in the scope in appending claims.
Claims (20)
1. TDMA method comprises step:
Modulate a kind of training sequence; With
The said training sequence of modulating produces a kind of TDMA burst sequence to data-signal by superposeing.
2. according to the TDMA method of claim 1, it is characterized in that,
Wherein, said training sequence is used to calculate the parameter of a kind of impulse response of transmission channel.
3. according to the TDMA method of claim 1 or 2, it is characterized in that,
Wherein said launching technique is used in gsm system or DCS system.
4. according to each the TDMA method in the claim of front, it is characterized in that,
Wherein said training sequence is used to estimate variation and/or the frequency error at TDMA burst sequence upper signal channel impulse response.
5. according to each the TDMA method in the claim of front, it is characterized in that,
Wherein said training sequence is CAZAC sequence or M sequence.
6. according to each the TDMA method in the claim of front, it is characterized in that,
The wherein said training sequence of modulating is added on the data-signal of being modulated to produce said TDMA burst sequence.
7. according to the TDMA method of claim 6, it is characterized in that,
The power of the wherein said training sequence that is applied is less than the said data-signal power of modulating.
8. according to each the TDMA method in the claim of front, it is characterized in that,
Wherein said training sequence repeats on the length range intercycle ground of described TDMA burst sequence.
9. according to each the TDMA method in the claim of front, it is characterized in that,
The power of the wherein said training sequence that is applied is less than said data-signal power.
10. be used for the transmitter of tdma system, comprise:
Be used to modulate the modulating device (3) of training sequence;
Be used for by superpose the said training sequence of modulating on the data sequence to produce the stacking apparatus of TDMA burst sequence; With
Be used to launch the emitter (6) of said TDMA burst sequence.
11. the transmitter according to claim 10 is characterized in that,
Wherein said training sequence separates modulation at said modulating device (3) and said data-signal.
12. the transmitter according to claim 10 or 11 is characterized in that,
Comprise another modulating device (2) that is used to modulate said data-signal.
13. each the transmitter according to claim 10 to 12 is characterized in that,
Comprise the attenuator (4) that is used for being added to the said training sequence of modulating that decay before the said data-signal provides from said modulating device (3).
14. the transmitter according to claim 13 is characterized in that,
Wherein said attenuator (4) is adjustable.
15. be used for the receiver of tdma system, comprise:
Be used to receive the receiving system (7) of TDMA burst sequence;
Be used to extract the extraction element (11) that is superimposed upon the training sequence on the TDMA burst sequence that is received; With
Be used for before Data Detection, removing the removal device (9) of the training sequence that is superposeed.
16. the receiver according to claim 15 is characterized in that,
Wherein said extraction element (11) comprises the filter that is used to extract said training sequence.
17. the receiver according to claim 16 is characterized in that,
Wherein said filter is a kind of sef-adapting filter.
18. each the receiver according to claim 15 to 17 is characterized in that,
Wherein said extraction element (11) is applicable to the parameter according to the described training sequence measured channel impulse response that extracts.
19. the receiver according to claim 18 is characterized in that,
Wherein the parameter of said described channel impulse response is provided for said removal device (9), and this device is applicable to according to the described parameter utilization that provides and disturbs the removal technology to remove said training sequence from the said TDMA burst sequence that receives.
20. the receiver according to claim 18 or 19 is characterized in that,
Comprise the detector (10) that is used for carrying out Data Detection according to the described channel impulse response parameter that is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 96199426 CN1206521A (en) | 1996-11-13 | 1996-11-13 | Method, transmitter and receiver for transmitting training signals in TDMA transmission system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 96199426 CN1206521A (en) | 1996-11-13 | 1996-11-13 | Method, transmitter and receiver for transmitting training signals in TDMA transmission system |
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| CN1206521A true CN1206521A (en) | 1999-01-27 |
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| CN 96199426 Pending CN1206521A (en) | 1996-11-13 | 1996-11-13 | Method, transmitter and receiver for transmitting training signals in TDMA transmission system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1298125C (en) * | 2003-02-26 | 2007-01-31 | 电子科技大学 | A Turbo method for eliminating trainning sequence |
| WO2014000259A1 (en) * | 2012-06-29 | 2014-01-03 | 华为技术有限公司 | Optical burst signal receiving method and device, and optical burst signal receiver |
| CN104040926A (en) * | 2012-11-19 | 2014-09-10 | 华为技术有限公司 | Modulation mode identification method, sending device, receiving device and system |
-
1996
- 1996-11-13 CN CN 96199426 patent/CN1206521A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1298125C (en) * | 2003-02-26 | 2007-01-31 | 电子科技大学 | A Turbo method for eliminating trainning sequence |
| WO2014000259A1 (en) * | 2012-06-29 | 2014-01-03 | 华为技术有限公司 | Optical burst signal receiving method and device, and optical burst signal receiver |
| CN104040926A (en) * | 2012-11-19 | 2014-09-10 | 华为技术有限公司 | Modulation mode identification method, sending device, receiving device and system |
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